for the stuffing:

method

1. First prepare stuffing. Melt a knob of butter in a pan. Add the onion and fry gently for 5 minutes or until golden. Transfer to a mixing bowl and combine with the remaining stuffing ingredients.

2. Lay the mackerel flat on a board and sprinkle the flesh with lemon juice, and salt and pepper to taste. Spoon the prepared stuffing into the fish and reshape.

3. Place in an ovenproof casserole, barely cover the bottom of the dish with water and add the bay leaf and more salt and pepper to taste.

4. Cover the casserole with a lid, or greased greaseproof paper or foil and poach in a warm oven (160°C/325°F or Gas Mark 3) for 15 to 20 minutes or until the fish feels tender when pierced with a skewer.